breaks and in the periphery at the vitreous base. The retina should be flattened intraoperatively by using perfluorocarbon liquid or by draining internally through an existing peripheral retinal break, and laser treatment should be applied. A tamponade of sufficient duration should be used to allow the chorioretinal adhesion to form. Thus, the vitrectomy instrumentation should provide excellent illumination to be able to visualize retinal breaks and excellent cutting characteristics to remove vitreous traction at retinal breaks and lattice degeneration.

For more complex forms of retinal detachment such as giant retinal tears and retinal detachments complicated by proliferative vitreoretinopathy, the factors such as illumination and cutting are even more critical especially in visualizing and peeling epiretinal membranes. The use of silicone oil is more common in theses cases and it is difficult to do a direct perfluorocarbon liquid to silicone oil exchange. Often with small-gauge techniques, the surgeon does a fluid–air exchange followed by instillation of silicone oil [48, 70]. In some cases where the use of silicone oil is anticipated preoperatively, it may be reasonable to use a 20-gauge silicone oil cannula for the infusion while still using other sclerotomy openings at 23 or 25 gauge.

10.2.4.4 Pediatric Vitreoretinal Surgery

The smaller gauge instrumentation would seem to be ideal for pediatric vitreoretinal surgery, and this modality has been popular for both the management of pediatric cataracts and retinal cases [25, 60, 79, 80]. The smaller size offers greater advantages in the newborn and pediatric eye, especially in cases of retinopathy of prematurity.

Table 10.2 Complications of minimally invasive vitrectomy [13, 18, 24, 81–91]

Cataract

Choroidal hemorrhage or infusion

Retinal tear or detachment

Vitreous incarceration

Hypotony

Chronic macular hypotony and choroidal folds Increased risk of endophthalmitis

Dislodged 25-gauge cannula intravitreally Subconjunctival silicone oil

sutureless conjunctival incision has been thought to provide a direct route of entry for bacterial infection. Some early studies have reported a 12-fold increase in the rate of endophthalmitis compared with conventional 20-gauge vitrectomy [92]. Another study reported almost a 30-fold higher incidence with 25-gauge vitrectomy [89]. Other series have not reported any greater risk [93–95]. Of note is that early reports on the higher incidence of postoperative endophthalmitis have focused attention on ways to decrease the infection rate. We believe that measures such as the oblique insertion of the trocar/cannula to create a longer biplane incision, the meticulous surgical preparation with povidone iodine, the displacement of the overlying conjunctiva, and a lower threshold for suturing leaky sclerotomies, all contribute to lowering the rate of endophthalmitis.

A higher incidence of retinal detachment following 25-gauge vitrectomy has been debated. In one study, the rate of retinal tears after 25-gauge vitrectomy was half of the rate observed in 20-gauge cases (3.1 vs. 6.4%) but this difference was not statistically significant [88].

10.2.5 Complications

The complications reported from the use of small gauge vitrectomy are listed in Table 10.2, and in most instances do not appear to differ from those reported with conventional 20 gauge vitrectomy. The complication of greatest concern has been the rate of postoperative endophthalmitis [91]. Vitreous prolapse into the sclerotomy openings has been observed [90] and the

10.2.6Future Developments in Minimally Invasive Vitrectomy

Further advances in small-incision vitrectomy resulted in improvements in vitreous cutter technology (mentioned above), and using even smaller gauge instruments. Twenty-seven gauge instruments have been proposed for removal of macular puckers, so that minimal vitreous would be removed [96]. The retention of vitreous reduces the rate of progression of nuclear cataract postoperatively, for up to 5 years, and possibly